Structure and performance control of plant fiber based foam material by fibrillation via refining treatment

Plant fiber based foam materials have the potential for replacing traditional plastic analogs because of their biodegradability, recyclability, and abundance. However, the relatively large size of plant fibers results in large bubble formation during foaming due to weak hydrogen bonding between the fibers. In turn, this feature translates into a lack of pore uniformity and poor mechanical strength of the ultimately formed foams, thus hindering their potential applications. In this study, we designed a simple and inexpensive procedure of cellulosic foam material production by subjecting plant fibers (wood pulp) to a controlled fibrillation treatment called “beating,” while varying their binding to smaller fibrils produced by beating. The effects of the degree of fibrillation on the foaming material structure and performance were investigated. Based on microscopic observations, the foam structure was most suitable at the 60 °SR (degree of beating), featuring high pore density, internal bonding strength and porosity. The original plant fibers provided the material backbone while the fine fibrils formed by beating strengthened the foam structure through hydrogen bonding. The measured compressive cushioning properties were also found to be optimal at this degree of fibrillation.